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Difference Between Viruses and Viroids

A virus is defined as an ineffective agent that consists of nucleic acid in a protein coat, and it’s usually too small to be seen through a microscope. It is also able to multiply only within the living cells of a host. Viroids, on the other hand, are defined as the smallest known pathogens that are composed of short strands of circular single-stranded RNA and don’t contain a protein coat (Seligmann, pg. 5). The viroid RNA does not encode any gene product which prevents them from replicating themselves. They can only be reproduced by the host cell, which is dependent on the RNA polymerase.

There exist several differences between these two. One of the differences is that the virus can infect animals, plants, and even bacteria, while the viroid is only able to infect plants. The second difference is that viruses have a protein coat, while viroids don’t have this protein coat (Seligmann, pg. 3). The other difference is that viruses are nucleoprotein particles, whereas viroids are infectious RNA particles. A virus can either be DNA or RNA, but with the viroid, it is only formed from RNA (Patiño Galindo, np). The virus tends to have a larger size, whereas the viroid tends to have a smaller size. A virus may come in different shapes and sizes, whereas a viroid occurs only in a circular form.

Of these two, the one that causes more threat to the human body is the virus since viroid can’t infect human beings. Some of the viruses and the diseases they cause in the human body include the Hepatitis B Virus, which is the cause of hepatitis (Patiño Galindo, np). Another one is the Yellow Fever virus, which is known to cause the disease known as yellow fever, and another one may include the Human Immunodeficiency Virus, which is known to cause AIDS.

Works Cited

Patiño Galindo, Juan Ángel, Fernando González Candelas, and Oliver G. Pybus. “The effect of RNA substitution models on viroid and RNA virus phylogenies.” Genome biology and evolution (2018).

Seligmann, Herve, and Didier Raoult. “Unifying view of stem–loop hairpin RNA as origin of current and ancient parasitic and non-parasitic RNAs, including in giant viruses.” Current opinion in microbiology 31 (2016): 1-8.



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